A hydraulic system by Rexroth makes new sintering process possible

A hydraulic system by Rexroth makes new sintering process possible
Marginal Column
Content

November 2016

 

With a new sintering process, GeniCore is transforming metal powder into carbide. A hydraulic system from Rexroth ensures that the pressure is constantly high.

New materials are conquering the world every day. The requirements placed on them continue to increase: They should be environmentally friendly, affordable, and globally available. Hard metals are especially needed for tools such as saw blades, drills and cutters. Sintering is a popular technique used in their production. It involves compressing metal powder under high pressure and at high temperatures to form a solid workpiece. The Polish machine manufacturer GeniCore has developed a new process specifically for this application: PulsePlasmaCompaction, or PPC for short. It enables workpieces to be produced from various powders. Diamond-reinforced carbides are created, among others. Up to now these were manufactured by means of high pressure-high temperature synthesis. However, this procedure had one decisive disadvantage: It was extremely costly. In addition, clumps also formed frequently in the material during the production of diamond enhanced carbide. This resulted in material that was inhomogeneous and the special properties of the nanocrystalline metal were destroyed. The special sintering process from GeniCore solves these problems. A strong vacuum, high voltage and powerful, short electronic impulses form the basis for the manufacturing of metals with a homogeneous structure. Precise control and high pressure are crucial for the manufacturing process.

The hydraulic system from Rexroth ensures constant high pressure in the sintering system from GeniCore.

The hydraulic system from Rexroth ensures constant high pressure in the sintering system from GeniCore.

 

Constant high pressure

The company opted for a hydraulic system from Rexroth for its PPC sintering plant. The most important requirement throughout the entire process was a wide range of constant forces ranging from 0.3 to 20 tons. At its heart is a 6.6 kilowatt electric motor, which drives a gear double pump. The first pump with a displacer volume of 22 cubic centimeters per rotation ensures continuous bypass filtration and cooling of the equipment. It also drives the pressing cylinder when there are rapid tooling movements. The second pump with a displacer volume of 3.2 cubic centimeters per rotation drives the system while the power is being adjusted during the pressing process. The pressing cylinder movement is also adjusted at slow speed.

Stable and accurate

The central control element is a directly-operated 4/4 directional control valve with integrated control electronics and a piston with zero overlap and linear characteristic curve. When the enable signal is activated, the piston moves into its working position, where it produces pressure in both chambers of the cylinder and creates the required press capacity. The stability and accuracy of these forces is crucial for the pressing process. The outcome is high-quality carbides with the best material properties.